From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Brauner Subject: Re: [PATCH net-next 14/20] net/neighbor: Update neigh_dump_info for strict data checking Date: Sun, 7 Oct 2018 12:46:16 +0200 Message-ID: <20181007104614.u3mfpw7foluztufj@brauner.io> References: <20181004213355.14899-1-dsahern@kernel.org> <20181004213355.14899-15-dsahern@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: netdev@vger.kernel.org, davem@davemloft.net, jbenc@redhat.com, stephen@networkplumber.org, David Ahern To: David Ahern Return-path: Received: from mail-wr1-f65.google.com ([209.85.221.65]:41045 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726264AbeJGRxQ (ORCPT ); Sun, 7 Oct 2018 13:53:16 -0400 Received: by mail-wr1-f65.google.com with SMTP id x12-v6so17699940wru.8 for ; Sun, 07 Oct 2018 03:46:23 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20181004213355.14899-15-dsahern@kernel.org> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Oct 04, 2018 at 02:33:49PM -0700, David Ahern wrote: > From: David Ahern > > Update neigh_dump_info for strict data checking. If the flag is set, > the dump request is expected to have an ndmsg struct as the header > potentially followed by one or more attributes. Any data passed in the > header or as an attribute is taken as a request to influence the data > returned. Only values supported by the dump handler are allowed to be > non-0 or set in the request. At the moment only the NDA_IFINDEX and > NDA_MASTER attributes are supported. > > Existing code does not fail the dump if nlmsg_parse fails. That behavior > is kept for non-strict checking. > > Signed-off-by: David Ahern > --- > net/core/neighbour.c | 59 ++++++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 48 insertions(+), 11 deletions(-) > > diff --git a/net/core/neighbour.c b/net/core/neighbour.c > index b06f794bf91e..3130d010b7ad 100644 > --- a/net/core/neighbour.c > +++ b/net/core/neighbour.c > @@ -2428,13 +2428,14 @@ static int pneigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb, > > static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb) > { > + struct netlink_ext_ack *extack = cb->extack; > const struct nlmsghdr *nlh = cb->nlh; > struct neigh_dump_filter filter = {}; > struct nlattr *tb[NDA_MAX + 1]; > struct neigh_table *tbl; > int t, family, s_t; > int proxy = 0; > - int err; > + int err, i; > > family = ((struct rtgenmsg *)nlmsg_data(nlh))->rtgen_family; > > @@ -2445,20 +2446,56 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb) > ((struct ndmsg *)nlmsg_data(nlh))->ndm_flags == NTF_PROXY) > proxy = 1; > > - err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL, > - cb->extack); So right, this seems like there was precedent in the kernel where an nlmsg_parse() would fail and a warning as generated in the logs. Anyway, as we have decided to not cause such warnings to be printed it would make sense to make the whole nlmsg_parse() conditional and move it under the if (strict) branch. > - if (!err) { > - if (tb[NDA_IFINDEX]) { > - if (nla_len(tb[NDA_IFINDEX]) != sizeof(u32)) > - return -EINVAL; > - filter.dev_idx = nla_get_u32(tb[NDA_IFINDEX]); > + if (cb->strict_check) { > + struct ndmsg *ndm; > + > + if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) { > + NL_SET_ERR_MSG(extack, "Invalid header"); > + return -EINVAL; > + } > + > + ndm = nlmsg_data(nlh); > + if (ndm->ndm_pad1 || ndm->ndm_pad2 || ndm->ndm_ifindex || > + ndm->ndm_state || ndm->ndm_flags || ndm->ndm_type) { > + NL_SET_ERR_MSG(extack, "Invalid values in header for dump request"); > + return -EINVAL; > } > - if (tb[NDA_MASTER]) { > - if (nla_len(tb[NDA_MASTER]) != sizeof(u32)) > + } > + > + err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL, extack); > + if (err < 0) { > + if (cb->strict_check) > + return -EINVAL; > + goto walk_entries; > + } > + > + for (i = 0; i <= NDA_MAX; ++i) { > + if (!tb[i]) > + continue; > + switch (i) { > + case NDA_IFINDEX: > + if (nla_len(tb[i]) != sizeof(u32)) { > + NL_SET_ERR_MSG(extack, "Invalid IFINDEX attribute"); > return -EINVAL; > - filter.master_idx = nla_get_u32(tb[NDA_MASTER]); > + } > + filter.dev_idx = nla_get_u32(tb[i]); > + break; > + case NDA_MASTER: > + if (nla_len(tb[i]) != sizeof(u32)) { > + NL_SET_ERR_MSG(extack, "Invalid MASTER attribute"); > + return -EINVAL; > + } > + filter.master_idx = nla_get_u32(tb[i]); > + break; > + default: > + if (cb->strict_check) { > + NL_SET_ERR_MSG(extack, "Unsupported attribute in dump request"); > + return -EINVAL; > + } > } > } > + > +walk_entries: > s_t = cb->args[0]; > > for (t = 0; t < NEIGH_NR_TABLES; t++) { > -- > 2.11.0 >